A couple of suggestions:
1: For the run animation use less lateral movement. Maybe just a tiny hint of one. With a slight rise and fall (vertical movement) over the animations lenght. I divide an animtion in to 4 parts. Start and finish are the same (for looping). 1/4 of the way I have it rise or fall a little. then 3/4 of the way I have it go the opposite direction. With graduated steps inbetween (which I do not keyframe). This gives a gentle hover like effect and makes it look like the unit is flying.
2: Jet engines are not dark or black when a plane is under way. Look at any of the other planes on here my Wyrmshadow, Ripptide, me etc and you will see they all have some fire/glow from the jets.
General: always include at least a run, death and attack (for units that have an attack). Ideally you can include more, but those extras are just that... nice extras.